Turbo Boost

[jimkate]

My 1995 Monaco Dynasty has 12 valve 8.3 Cummins with Banks Stinger kit. I'm getting at maximum about 12 lb turbo boost. Is this right?

[csp]

You should be getting around 23 pounds of boost. You could have a problem with fueling, turbo, or a problem with the boost gauge or you are loosing boost before it gets to the engine. The 8.3 Cummins makes @13hp per pound of boost. 23 pounds of boost times 13 gives you 299hp. If you do not have a gauge leak that means you have only 156hp. The stinger kit alone adds 75hp and 151torque. The is a Banks web site for the stinger kit Exhaust - Banks Power - 8.3 Stinger® System Pusher Motorhome - The Power Shop - MORE POWER TO YOU.
Remember once you figure out your problem if you do any fueling modifications if you still have the HX40 turbo, do not let it spool close to 40 pounds of boost very much because I have heard they will not live very long. I have mine set so it gets 35 pounds of boost. Mine should be around 455hp(it runs pretty good). Another thing you need to watch if you modify the fueling is EGTs. Mine climbing a mountain with the pedal on the floor it barely gets over 1200 degrees. Aluminum pistons melt at 1350 degrees.
Hope this helps you out.
Chris

[Ray,IN]

First thing to look for is air leakage at rubber hoses on the intake piping.

[csp]

jimkate
What did you find wrong with your RV? Please give an update.
Chris

[Ray,IN]

I sent jimkate a PM about his question. Here is his reply_ by PM:

Quote:
Originally Posted by Ray,IN
What did you find out about your boost question?


I'm not satisfied with what I've heard so far. When I first started driving my coach, I was surprised that the boost is so low. Max 12lb. However, under full load, I have to watch the exhaust temperature to make sure it doesn't slide up too high (Above 1300deg). I may find the cpl of the engine and try to contact Cummins, or contact Banks themselves for some insight.

I'm an agricultural diesel mechanic by trade. Here's what I suspect. I think the engine I have is basically a naturally aspirated engine that a turbo was bolted on to. Fine, if you keep the boost real low. Then a Banks system was installed, which raised the boost a little bit, and increased the fuel a little bit, enough that you have to watch the exhaust temperature gauge.

What needs to be done to realize any real power gain is install an intake intercooler to get the air temperature down, then raise the turbo boost, possibly open the fuel a little, and probably open up the exhaust system to let the air flow freely.
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I would suggest that installing a larger exhaust system (turbo-back) will greatly decrease the EGT issue. A diesel engine requires air in- air out. One cannot increase intake air, and/or fuel without also increasing exhaust air flow(larger exhaust piping).
Of course any advice any of us may offer is in vain if the OP doesn't return to read responses to the question.

[Steve Ownby]

Hi Ray,

I don't understand the PM from jimkate. Cummins started turbocharging their engines in 1952 and they use a CAC. His whole premise seemed off track. I agree with your first answer to him about a leak in one of the 4" couplings in the CAC plumbing. Or his gauge could just be faulty. I would think his performance would be noticeably down at 12 psi boost.

Steve O

[RJRobb]

Do you have an exhaust brake? It's possible the brake is malfuctioning (stuck closed or partially) which would cause low boost, high egt, and performance issues.

[csp]

Good thinking RJRobb. If you can not get rid of the air because of the exhaust brake on or partially on the turbo will not spool up because of back pressure.
Chris

[jimkate]

Hey guys. Thanks for the input. I think you've nailed it with the exhaust brake issue, because I've been thinking that my exhaust brake is not working right. My coach is laid up right now, but I'm getting it in for some service work in a few weeks, I'm going to check that and report back to you about it.